On Thursday 29 June 2017 19:02:38 Cecil Thomas wrote: > Gene, > I think you are dealing with ringing as opposed to chatter. Chatter > is usually a low frequency vibration caused by the tool biting in and > releasing repeatedly. The frequency and intensity will change as you > change spindle speed, cutting depth and feed rate. > > Ringing on the other hand is just like the ringing in an LC > circuit. It is a function of the stiffness of the material, its > diameter, its length and how it is restrained at each end. Given an > appropriate text book and a calculator you can actually calculate > what the frequency should be. The only way to stop the ringing is to > add damping, a lossy element (resistor)to dissipate the energy. > > Think about a bell or a guitar string. As long as the work piece is > significantly longer than its diameter it will ring like a bell. > The only way to stop the ringing is to absorb the vibrations, think > putting your hand on the guitar string. I have solve "ringing" > problems by working only on one half or less of the stock and > sticking gobs of modeling clay on the other half and wrapping all > that up with duct tape. That kills the vibration. when I finish the > first half I move the "damper" to the other end. > > The simplest way is to use a follower rest. That stops the vibration > immediately. Didn't you get a follow rest with the lathe? > This might call for a few manual passes with the follow rest before > you get fancy with the CNC. That's why I insist that my CNC > conversions retain handwheel operation. > > Cecil
I think you're right, and yes I have both steady and follower, but nut enough workpiece length to make use of them. And I still have cranks, but they are mpja encoder wheels that I can set to is little as .0005" per click. I have the part turned to a much better major diameter, which when turned around in the chuck, ought to be much more rigid than it now is as its being gripped on an about 3/8" extension that will be turned off eventually. If I even use it. I found a mounted stone this afternoon, which if I can source more of, might be just what Dr. Gene wrote on the prescription pad. I have already mounted a big HF die grinder to an AXA toolholder. The toolpost, a plunger style Phase-II, is being a problem child, not wanting to pull the plunger in to release the toolholder on one face, and the pad holding screw feels gauled or something in the plunger as it comes loose but will not come clear out. Fells like its full of grit and eventually starts spinning the plunger, or feels like it. Do you have any ideas on how to disassemble and clean/lube one of those? > > At 06:12 PM 6/29/2017, you wrote: > >yes, momentarily Andy, but it right back as soon as the speed > > steadies, at rpms from 50 to 600. And the oscillation frequency is > > quite constant over that range. Feeling the spinning workpiece, its > > much stronger there, than anyplace else. > >---------------------------------------------------------- > >Check out the vibrant tech community on one of the world's most > >engaging tech sites, Slashdot.org! http://sdm.link/slashdot > >_______________________________________________ > >Emc-users mailing list > >[email protected] > >https://lists.sourceforge.net/lists/listinfo/emc-users > > ---------------------------------------------------------------------- >-------- Check out the vibrant tech community on one of the world's > most engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
